1. Field of the Invention
The present invention relates to a printer capable of detecting the status of unutilized ribbon, more particularly, to a printer capable of elongating the ribbon between a print head and a ribbon supply end to detect the status of the unutilized ribbon.
2. Description of the Prior Art
A printer has become an essential output device in our information age. A traditional printer prints data onto a piece of paper or a print medium. As information technology advances, printers nowadays come with a variety of functions. For example, a thermal printer is capable of printing an image directly from a digital camera onto a piece of paper, the advantage is that a user can choose to print a favorite image or photograph and discard the rest. Therefore wasting resources and money to develop a full roll of traditional negatives to print photographs is avoided. The current thermal printer, utilizes a thermal print head to print documents, includes a paper drawer for placing print material such as paper, and an imaging material cassette for placing imaging material such as ink film or ribbon.
The thermal and ink jet printers have very similar frameworks, however, one difference being that the ink jet printer requires liquid ink whereas the thermal printer utilizes a solid ribbon. Another difference is that most ink jet printers utilize a half tone printing method; they are unable to print continuous tone of a real life photograph. Hence, the thermal printer that has a continuous tone function is becoming more popular among consumers. The thermal printer utilizes a sublimation technique to apply colors of the transfer ribbon directly onto the paper; the ribbon is a transparent cellular paper that includes dye. During the process of printing, the thermal print head heats the ribbon's dye. The melted color will be transferred from the ribbon onto the paper. Later when the color on the paper cools a colored image will be displayed.
In general, to ensure that there is sufficient ribbon for the next printout, there is a need to detect if the ribbon is reaching its end. In determining a conventional group of ribbon, a special barcode is added to the ribbon for the optical sensor to differentiate. Please refer to FIG. 1. FIG. 1 illustrates a perspective view of a ribbon apparatus of a conventional color printer 10. As shown in FIG. 1, the ribbon apparatus of the color printer 10 comprises a ribbon 12, two light sources 14, 16, and two sensors 18, 20. The ribbon 12 comprises a plurality of sequentially arranged dye regions 22. Each dye region 22 comprises four different color dye areas 24, 26, 28, 30 for placing yellow dye, magenta dye, cyan dye, and overcoating dye. An opaque dividing section 32 is located before a yellow dye area 24. A semi-opaque dividing section 34 and a transparent dividing section 36 are located between the dye areas 24 and 26, 26 and 28, 28 and 30. The light sources 14, 16 are located on one side of the ribbon 12 and produce light beams 38, 40 of two predetermined colors. The sensors 18, 20, corresponding to the light sources 14, 16, are located on the opposite side of the ribbon 12. The sensors 18, 20 are utilized to detect light beams 38, 40 penetrating through the ribbon 12 and produce corresponding signals to determine the position of the ribbon 12. The detection of an opaque dividing section 32 signals the beginning position of a new dye region 22 of the ribbon 12, and also corresponds to the beginning position of a yellow dye area 24. The detection of a semi-opaque dividing section 34 and a transparent dividing section 36 by the sensors 18, 20 corresponds to the beginning position of the magenta dye area 26, cyan dye area 28, or overcoating dye area 30. In the above-mentioned, a special barcode is added to the opaque dividing section 32 before a group of dye area 22 on the ribbon 12. The detection of the special barcode signals a last unused dye area 22 and to remind the user to replace the existing ribbon 12. In this method of detecting ribbon, the special barcode is needed to place in between each dye area, and it decreases the effective utilization of the ribbon 12, resulting in higher production costs of the ribbon 12.